games
Trust game
You can send part of $10. What you send is tripled.
Player 1 is given $10 and can send any amount to Player 2. Whatever is sent is tripled. Player 2 then decides how much of the tripled money to send back to Player 1. Player 1 moves first and must trust that Player 2 will return something.
You are Player 1. How much do you send to the other player?
If both players only care about their own money, Player 2 returns nothing, and Player 1 should send nothing.
In experiments many Player 1s send a substantial amount, and many Player 2s return enough to reward the trust.
The game measures willingness to trust and willingness to reciprocate when there is no enforcement.